Using the definitional procedures delineated by the Diagnostic and Statistical Manual III as well as social system definers and other empirical methods for defining hyperactivity, the investigators propose to 1) characterize the subgroups of children created using each definitional procedure based on the following predispositional factors: family characteristics, health history, temperament, home environment, parent attitudes toward hyperactivity, and treatment history of hyperactivity and in this way clarify the nature of the definitional procedures in terms of the contributions of the various etiological factors. We also intend to 2) determine and compare the nature of adolescent outcomes for subgroups of children created using each definitional procedure. The outcomes of interest are evidence of delinquency, antisocial behavior, anxiety depression, academic failure, and persistence of hyperactive or other problem behaviors. Accomplishing this goal will allow us to evaluate the theoretical and predictive utility of the different definitional systems. Finally, we propose to 1) define those factors that mediate the nature and severity of adolescent outcomes. The factors that are seen as having a potentially mediating role are cognitive development, social role functioning, peer relationships, self-satisfaction, attitude toward one's hyperactivity, locus of control, and the ongoing quality of the home and school environment.